EP4090715A1

EP4090715A1 - Sealing tape bonding weakly or not at all on one side

Info

Publication number: EP4090715A1
Application number: EP21702168.2A
Authority: EP
Inventors: Li Wang; Deniz Nick Akin; Kim ELSENBACH; Hannes DAG
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2020-01-15
Filing date: 2021-01-15
Publication date: 2022-11-23
Also published as: DE102020200452A1; WO2021144414A1; US20230053665A1; CN114929824A

Abstract

The invention relates to a sealing element with high sealing effect against air and moisture, which is easy to apply, and which moreover offers the possibility to reopen the sealed gap in an uncomplicated manner. Said solution is provided by an adhesive tape with differing adhesive power on the two main sides, which comprises a) a polymer foam layer and b) an outer adhesive compound layer and/or an outer thermoplastic film on one side of the polymer foam layer and is characterized in that, where the adhesive tape comprises an outer adhesive compound layer, the tape has a greater adhesive power on the side provided with the outer adhesive compound layer than on the opposing side and/or, where the adhesive tape comprises an outer thermoplastic film, the tape has a lower adhesive power on the side provided with the outer thermoplastic film than on the opposing side. The invention furthermore relates to the use of an adhesive tape according to the invention for sealing a joint between two components.

Description

description

Sealing tape weakly or non-adhesive on one side

The invention relates to the technical field of adhesive tapes, as they are often used in households and in industry for joining two substrates, but also for other purposes such as protecting surfaces or for sealing. More specifically, a foam adhesive tape suitable for sealing is proposed which has different adhesive strengths on its two main sides or is provided with pressure-sensitive adhesive on only one of its two main sides.

Seals are required for many constructions in different fields of technology, for example in construction and in vehicle construction. The sealing elements used for this purpose should often seal gaps, which are almost inevitable when connecting two components, against the ingress of moisture and air, in order to protect the parts behind them from damage caused by this, e.g. from corrosion. Mechanical connections, such as those made by screws, are usually not able to produce a sufficient seal.

For this reason, silicone sealants, for example, are often used in order to achieve a suitable seal for the connections made. Such sealing compounds can be processed quite reliably, but require a certain time to harden and thus often cause process engineering difficulties. The situation is similar with other structural adhesives or sealants, e.g. those based on epoxides or polyurethanes.

Silicone foams are also used as sealing compounds; they are characterized by good flame retardant properties and their reusability. On the other hand, it is difficult to process them in an automated process, and they are also comparatively expensive. Butyl sealing compounds are established and inexpensive, on the other hand difficult to control with regard to their dosage and not very resistant to aging. In addition, they are often squeezed out of the gap at higher pressures.

Elastic sealants such as rubbers or styrene-butadiene rubbers offer proven sealing properties and are also very temperature-stable. Since they are not self-adhesive, however, their handling is rather difficult; In addition, they are inflexible, so the respective sealing element must fit exactly to the gap to be sealed.

Polyurethane foams show good compression behavior and can be processed automatically; so-called foam / n-p / ace applications are also possible. Fluctuations in the dimensions of the foam in question are disadvantageous, and these substances are also susceptible to corrosion and degradation under the influence of certain cleaning agents.

EPDM foams show a similar profile of properties; Even with them, only a limited sealing effect can be achieved because of their irregular surface design.

In contrast, WO 2009/086056 A2 describes what is known as a flashing tape, which is intended to exclude moisture in structural applications. The disclosed structure of the tape comprises a viscoelastic core layer and at least one elastomeric outer layer; In addition, a pressure-sensitive adhesive layer can be included in order to adhere the tape to a substrate.

There is a continuing need for well applicable systems for sealing connections between two components. The object of the invention was therefore to provide a sealing element which is easy to apply and has a high sealing effect against air and moisture and which also offers the possibility of uncomplicated reopening of the sealed gap.

A first and general object of the invention, with which this object is achieved, is an adhesive tape with different adhesive strength on both main sides, which has a) a polymer foam layer and b) an outer pressure-sensitive adhesive layer and / or an outer thermoplastic film on each side of the polymer foam layer; and is characterized in that, if the adhesive tape comprises an outer pressure-sensitive adhesive layer, it has a higher bond strength on its side equipped with the outer pressure-sensitive adhesive layer than on the opposite side and / or, if the adhesive tape comprises an outer thermoplastic film, it has a lower bond strength on its side equipped with the outer thermoplastic film than on the opposite side.

As has been shown, such an adhesive tape can advantageously be used to seal connections between components, on the one hand allowing simple, safe and precise application and on the other hand enabling simple dismantling of the connection. In addition, it can be processed automatically and shows a controlled compression behavior.

The general expression “adhesive tape” in the context of this invention includes all flat structures with one or both sides self-adhesive, such as films or film sections extended in two dimensions, tapes with extended length and limited width, tape sections, labels, diecuts and the like as well as corresponding multilayer arrangements.

Often adhesive tapes or their adhesives are covered or protected with what is known as a release liner, which is removed before the adhesive tape is applied. A release liner is not part of the adhesive tape, but only an aid for its production and / or storage.

Usually adhesive tapes are used

- in fixed lengths such as by the meter or

- made available as continuous goods in the form of rolls (Archimedean spiral) or coils wound on a core.

Polverschaumschicht

The adhesive tape according to the invention comprises a polymer foam layer. A “polymer foam layer” or a “polymer foam” is understood to mean a material with open and / or closed cells distributed over its entire mass, which has a bulk density that is lower than that of the polymeric framework. The term "foam" means in particular that the layer in question comprises structures of gas-filled, often spherical or polyhedral cells, which are delimited by liquid, semi-liquid, high viscosity or solid cell webs or their own shell material and which are in such a proportion in the layer in question present that the density of the foamed layer compared to the density of the matrix material, that is to say the entirety of the non-gaseous materials except for any own shell material of the foam cells that may be present.

The framework substance, also referred to below as polymer foam matrix, foam matrix, matrix or matrix material, is, according to the invention, one or more polymers which can be mixed with additives. “Open cells” are hollow spaces within the foam that are not completely surrounded by structural substance or a separate shell material. “Closed cells” are understood to mean cavities that are completely surrounded by structural substance or a separate shell material. The polymer foam layer of the adhesive tape according to the invention is preferably a closed-cell foam.

Generally preferably, the polymer foam layer, in particular the matrix material of the polymer foam layer, contains at least 35% by weight, more preferably at least 50% by weight and particularly preferably at least 70% by weight, in particular at least 80% by weight, for example at least 90% by weight, based in each case on the total weight of the polymer foam layer or the total weight of the matrix material, of one or more polymers. This polymer content can vary depending on the type of base polymer. Possible polymers of the polymer foam layer include polyolefins, for example polyethylenes such as high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and linear ultra low density polyethylene, polypropylene and polybutylene; Vinyl copolymers such as polyvinyl chloride and polyvinyl acetate; olefinic random or block copolymers, e.g. ethylene-methyl acrylate copolymers, ethylene-vinyl acetate copolymers and ethylene-propylene copolymers as well as ethylene-propylene-diene terpolymers (EPDM), also polyalkylenes, which are produced from monomer mixtures, which 1) a first alkene selected from ethylene, propylene or a mixture thereof, and 2) a second alkene selected from 1,2-alkenes having 4 to 8 carbon atoms such as 1,2-butene, 1,2-hexene or 1,2-octene ; Acrylonitrile-butadiene-styrene copolymers; Acrylic polymers and copolymers; Polycarbonates; Polyimides; Polyurethanes, for example thermoplastic polyurethanes, in particular polyester-based thermoplastic polyurethanes; Polyesters, for example polyethylene terephthalate; as well as combinations and blends of the aforementioned polymers. Exemplary blends include polypropylene-polyethylene blends, PVC-nitrile rubber blends, polyurethane-polyolefin blends, polyurethane-polycarbonate blends and polyurethane-polyester blends. Furthermore, blends of thermoplastic polymers, elastomeric polymers and combinations thereof can be included. Further blends can be styrene-butadiene copolymers, polychloroprene, e.g. neoprene, nitrile rubbers, butyl rubbers, polysulfide rubbers, cis-1,4-polyisoprene, ethylene-propylene terpolymers, e.g. EPDM rubber, silicone rubbers, Silicone-polyurea block copolymers, polyurethane rubbers, natural rubbers,

Acrylate rubbers, thermoplastic rubbers, e.g. styrene-butadiene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene / butylene-styrene block copolymers,

Styrene-ethylene / propylene-styrene block copolymers, thermoplastic polyolefin rubbers, and combinations thereof.

The polymer or polymers of the polymer foam layer, in particular the matrix material of the polymer foam layer, are preferably selected from the group consisting of polyolefins; Polyurethanes; Polyvinyl chloride (PVC); Blends of PVC and nitrile rubber; Terpolymers of ethylene, propylene and a non-conjugated diene (EPDM); Copolymers of ethylene and an ethylene substituted with a polar group; Blends of polyethylene and a polymer of an ethylene substituted with a polar group; Poly (meth) acrylates; Blends of poly (meth) acrylate and synthetic rubber and mixtures of two or more of the aforementioned polymers. The polymer foam layer, in particular the matrix material of the polymer foam layer, thus preferably contains at least 35% by weight, more preferably at least 50% by weight and particularly preferably at least 70% by weight, in particular at least 80% by weight, for example at least 90% by weight, based in each case on the total weight of the polymer foam layer or the total weight of the matrix material, one or more polymers selected from the group consisting of polyolefins; Polyurethanes; Polyvinyl chloride (PVC); Blends of PVC and nitrile rubber; Terpolymers of ethylene, propylene and a non-conjugated diene (EPDM); Copolymers of ethylene and an ethylene substituted with a polar group; Blends of polyethylene and a polymer of an ethylene substituted with a polar group; Poly (meth) acrylates; Blends of poly (meth) acrylate and synthetic rubber and mixtures of two or more of the aforementioned polymers. The matrix material of the polymer foam layer particularly preferably contains no further polymers apart from one or more polymers selected from the group consisting of polyolefins; Polyurethanes; Polyvinyl chloride (PVC); Blends of PVC and nitrile rubber; Terpolymers of ethylene, propylene and a non-conjugated diene (EPDM); Copolymers of ethylene and an ethylene substituted with a polar group; Blends of polyethylene and a polymer of an ethylene substituted with a polar group; Poly (meth) acrylates; Blends of poly (meth) acrylate and synthetic rubber and mixtures of two or more of the aforementioned polymers.

A “polyolefin” is a polymer of general structure

- [CH2-CRiR2-] n- understood, in which Ri and R2 independently of one another are a hydrogen atom or a linear or branched saturated aliphatic or cycloaliphatic group describe. The polyolefin is preferably polyethylene, polypropylene, polybutylene or a mixture of these. The polyethylene can be one or more of the polyethylene types known per se, such as HDPE, LDPE, LLDPE, VLDPE, VLLDPE, MDPE (medium-density PE), metallocene PE types such as mLLDPE and mHDPE, blends of these types of polyethylene and mixtures of which include. The polypropylene is preferably a crystalline polypropylene, more preferably a homopolypropylene (hPP). In a special embodiment I of the polymer foam layer, the matrix material of the polymer foam layer does not contain any further polymers apart from one or more polyolefins.

A copolymer of ethylene and an ethylene substituted by a polar group is understood to mean a polymer of the general structure - [CH2-CR3R4 -] n-, where R3 or R4 denote a hydrogen atom and the remaining substituent denotes a group containing at least one oxygen atom. The copolymer of ethylene and an ethylene substituted by a polar group is preferably an ethylene-vinyl acetate copolymer (EVA), an ethylene-methyl acrylate copolymer (EMA), an ethylene-ethyl acrylate copolymer (EEA), an ethylene-acrylic acid copolymer (EAA), an ethylene-butyl acrylate copolymer (EBA) or a mixture of these. The EVA preferably has a vinyl acetate content of 1 to 70% by weight, more preferably 3 to 30% by weight, in particular 5 to 20% by weight. In a more specific variant of embodiment I of the polymer foam layer, the matrix material of the polymer foam layer contains no further polymers apart from one or more copolymers of ethylene and an ethylene substituted by a polar group. In particular, the copolymer of ethylene and an ethylene substituted by a polar group is an ethylene-vinyl acetate copolymer (EVA). In this embodiment, the matrix material of the polymer foam layer particularly preferably contains at least one ethylene-vinyl acetate copolymer (EVA). In particular, the proportion of all ethylene-vinyl acetate copolymers in the matrix material of the polymer foam layer is at least 50% by weight, more preferably at least 70% by weight and particularly preferably at least 80% by weight, in particular at least 85% by weight, for example at least 90% by weight, based in each case on the total weight of the matrix material. The matrix material very particularly preferably contains no further polymers apart from one or more ethylene-vinyl acetate copolymers (EVA).

The matrix material of the polymer foam layer is preferably crosslinked. The crosslinking takes place preferably before the matrix material is foamed. Matrix materials which contain polymers selected from polyolefins and copolymers of ethylene and an ethylene substituted with a polar group are preferably crosslinked with electron beams. Chemical crosslinking methods are also possible, for example crosslinking via grafted silane residues with hydrolyzable groups, which are then influenced by Moisture and catalysis can react with one another; furthermore crosslinking via added silanes which contain a free-radically polymerizable double bond and can react with free radicals which are formed in the polymer chains; as well as crosslinking via added peroxides, which also react with radicals.

In one embodiment II of the polymer foam layer, the polymer foam layer, in particular the matrix material of the polymer foam layer, contains at least one poly (meth) acrylate. A “poly (meth) acrylate” is understood to mean a polymer which can be obtained by free-radical polymerization of acrylic and / or methacrylic monomers and optionally other copolymerizable monomers. In particular, a “poly (meth) acrylate” is understood to mean a polymer whose monomer base consists of at least 50% by weight of acrylic acid, methacrylic acid, acrylic acid esters and / or methacrylic acid esters, acrylic acid esters and / or methacrylic acid esters at least proportionally, preferably at least 30% by weight .-%, based on the total monomer base of the polymer in question, are included.

The polymer foam layer preferably contains a total of 40 to 99.9% by weight of poly (meth) acrylates, more preferably a total of 60 to 98% by weight, in particular a total of 75 to 95% by weight, for example a total of 80 to 90% by weight % By weight, based in each case on the total weight of the polymer foam layer. It can contain a (single) poly (meth) acrylate or several poly (meth) acrylates; The plural term “poly (meth) acrylates” thus includes - also in the continuation of the present description - in its meaning as well as the expression “as a whole” both the presence of a single poly (meth) acrylate and the presence of several poly (meth) acrylates .

The glass transition temperature of the poly (meth) acrylates is preferably <0 ° C, more preferably between -20 and -50 ° C. The glass transition temperature of polymers or of polymer blocks in block copolymers is determined according to the invention by means of dynamic scanning calorimetry (DSC). For this purpose, approx. 5 mg of an untreated polymer sample are weighed into a small aluminum crucible (volume 25 ml) and closed with a perforated lid. A DSC 204 F1 from Netzsch is used for the measurement. It is carried out under nitrogen for the purpose of inerting. The sample is first cooled to -150 ° C, then heated to +150 ° C at a heating rate of 10 K / min and then cooled again to -150 ° C. The subsequent second heating curve is run again at 10 K / min and the change in heat capacity is recorded. Glass transitions are recognized as steps in the thermogram. The poly (meth) acrylate preferably contains at least one partially polymerized functional monomer, particularly preferably reactive with epoxy groups with the formation of a covalent bond. The proportionately polymerized functional monomer, particularly preferably reactive with epoxy groups with formation of a covalent bond, contains at least one functional group selected from the group consisting of carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, hydroxyl groups, acid anhydride groups, epoxy groups and amino groups; in particular it contains at least one carboxylic acid group. The poly (meth) acrylate very preferably contains acrylic acid and / or methacrylic acid which has been partially polymerized into it. All of the groups mentioned have a reactivity with epoxy groups, as a result of which the poly (meth) acrylate is advantageously accessible to thermal crosslinking with introduced epoxides.

The poly (meth) acrylate can preferably be attributed to the following monomer composition: a) at least one acrylic acid ester and / or methacrylic acid ester of the following formula (1)

CH ₂ = C (R ^I ) (COOR ") (1), in which R '= H or CH 3 and R" is an alkyl radical having 4 to 18 carbon atoms; b) at least one olefinically unsaturated monomer with at least one functional

Group selected from the group consisting of carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, hydroxyl groups,

Acid anhydride groups, epoxy groups and amino groups; c) optionally further acrylic acid esters and / or methacrylic acid esters and / or olefinically unsaturated monomers which are copolymerizable with component (a).

It is particularly advantageous to use the monomers of component a) in a proportion of 45 to 99% by weight, the monomers of component b) in a proportion of 1 to 15% by weight and the monomers of component c) in a proportion from 0 to 40% by weight to be selected, the information being based on the monomer mixture for the base polymer without the addition of any additives such as resins, etc.

The poly (meth) acrylate can particularly preferably be attributed to the following monomer composition:

65 to 99% by weight of 2-ethylhexyl acrylate and / or n-butyl acrylate,

0 to 30% by weight methyl acrylate, 1 to 15% by weight acrylic acid.

The poly (meth) acrylate or the poly (meth) acrylates are preferably prepared by conventional free-radical polymerizations or controlled free-radical polymerizations. The poly (meth) acrylates can be prepared by copolymerizing the monomers using customary polymerization initiators and, if appropriate, regulators, polymerizing at the customary temperatures in bulk, in emulsion, for example in water or liquid hydrocarbons, or in solution.

The poly (meth) acrylates are preferred by copolymerizing the monomers in solvents, particularly preferably in solvents with a boiling range from 50 to 150 ° C., in particular from 60 to 120 ° C., using 0.01 to 5% by weight, in particular from 0.1 to 2% by weight, based in each case on the total weight of the monomers, of polymerization initiators.

In principle, all customary initiators are suitable. Examples of radical sources are peroxides, hydroperoxides and azo compounds, for example dibenzoyl peroxide, cumene hydroperoxide, cyclohexanone peroxide, di-t-butyl peroxide, cyclohexylsulfonylacetyl peroxide,

Diisopropyl percarbonate, t-butyl peroctoate, and benzpinacol. Preferred free-radical initiators are 2,2'-azobis (2-methylbutyronitrile) (Vazo® 67 ™ from DuPont) or 2,2'-azobis (2-methylpropionitrile) (2,2'-azobisisobutyronitrile; AIBN; Vazo® 64 ™ from DuPont).

Preferred solvents for the preparation of the poly (meth) acrylates are alcohols such as methanol, ethanol, n- and iso-propanol, n- and iso-butanol, in particular isopropanol and / or isobutanol; Hydrocarbons such as toluene and, in particular, gasolines with a boiling range from 60 to 120 ° C .; Ketones, especially acetone, methyl ethyl ketone, methyl isobutyl ketone; Esters such as ethyl acetate and mixtures of the abovementioned solvents. Particularly preferred solvents are mixtures which contain isopropanol in amounts of from 2 to 15% by weight, in particular from 3 to 10% by weight, based in each case on the solvent mixture used.

Preferably, after the production (polymerization) of the poly (meth) acrylates, there is a concentration, and the further processing of the poly (meth) acrylates is essentially solvent-free. The polymer can be concentrated in the absence of crosslinking and accelerating substances. However, it is also possible to add one of these classes of compound to the polymer even before the concentration, so that the concentration then takes place in the presence of this substance (s).

After the concentration step, the polymers can be transferred to a compounder. If necessary, the concentration and the compounding can also take place in the same reactor. Further processing after the concentration (Compounding) takes place preferably in one or more extruders. The mass is applied from the melt to an optionally temporary carrier material and formed into a layer by means of calender rollers.

The weight-average molecular weights M _{w of} the poly (meth) acrylates are preferably in a range from 20,000 to 2,000,000 g / mol; very preferably in a range from 100,000 to 1,500,000 g / mol, extremely preferably in a range from 150,000 to 1,000,000 g / mol. For this purpose it can be advantageous to carry out the polymerization in the presence of suitable polymerization regulators such as thiols, halogen compounds and / or alcohols in order to set the desired average molecular weight.

The details of the number-average molar mass M _n and the weight-average molar mass M _w in this document relate to the known determination by gel permeation chromatography (GPC). The determination is carried out on 100 ml clear-filtered sample (sample concentration 4 g / l). Tetrahydrofuran with 0.1% by volume of trifluoroacetic acid is used as the eluent. The measurement takes place at 25 ° C.

A column type PSS-SDV, 5 μm, 10 ³ Å, 8.0 mm ^* 50 mm (details here and below in the order: type, particle size, porosity, inner diameter ^* length; 1 Å = 10 ¹ ° m) used. A combination of columns of the PSS-SDV, 5 pm, 10 ³ Å, as well as 10 ⁵ Å and 10 ⁶ Å, each 8.0 mm ^* 300 mm, is used for separation (columns from Polymer Standards Service; detection using a Shodex RI71 differential refractometer ). The flow rate is 1.0 ml per minute. In the case of poly (meth) acrylates, calibration is carried out against PMMA standards (polymethyl methacrylate calibration) and otherwise (resins, elastomers) against PS standards (polystyrene calibration).

The poly (meth) acrylate preferably has a polydispersity PD <4 and thus a relatively narrow molecular weight distribution. In spite of a relatively low molecular weight, compositions based thereon have a particularly good shear strength after crosslinking. In addition, the lower polydispersity enables easier processing from the melt, since the flow viscosity is lower than that of a more widely distributed poly (meth) acrylate with largely the same application properties. Narrowly distributed poly (meth) acrylates can advantageously be prepared by anionic polymerization or by controlled radical polymerization methods, the latter being particularly suitable. Corresponding poly (meth) acrylates can also be produced via N-oxyls. Furthermore, atom transfer radical polymerization (ATRP) can advantageously be used for the synthesis of narrowly distributed poly (meth) acrylates, the initiator preferably being monofunctional or difunctional secondary or tertiary halides and, for the abstraction of the halides, Cu, Ni, Fe, Pd, Pt, Ru, Os-, Rh-, Co-, Ir-, Ag- or Au complexes can be used. RAFT polymerization is also suitable. The poly (meth) acrylates are preferably crosslinked by linking reactions - in particular in the sense of addition or substitution reactions - of functional groups contained in them with thermal crosslinkers. All thermal crosslinkers can be used that

- ensure a sufficiently long processing time so that gelation does not occur during the processing process, in particular the extrusion process,

- As well as lead to rapid post-crosslinking of the polymer to the desired degree of crosslinking at temperatures lower than the processing temperature, in particular at room temperature.

Thermal crosslinkers are preferably used in an amount of from 0.1 to 5% by weight, in particular from 0.2 to 1% by weight, based on the total amount of the polymer to be crosslinked.

Crosslinking via complexing agents, also known as chelates, is also possible. A preferred complexing agent is, for example, aluminum acetylacetonate.

The poly (meth) acrylates are preferably crosslinked by means of epoxide (s) or by means of one or more substance (s) containing epoxide groups. The substances containing epoxy groups are in particular multifunctional epoxides, that is to say those with at least two epoxy groups; accordingly, overall there is an indirect linkage of the building blocks of the poly (meth) acrylates which carry the functional groups. The substances containing epoxy groups can be both aromatic and aliphatic compounds.

Preferred epoxy crosslinkers are, for example, cycloaliphatic epoxides such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (UVACure1500).

The poly (meth) acrylates are particularly preferably crosslinked by means of a crosslinker-accelerator system (“crosslinking system”) in order to obtain better control over the processing time, the crosslinking kinetics and the degree of crosslinking. The crosslinker-accelerator system preferably comprises at least one substance containing epoxy groups as crosslinker and at least one substance that accelerates crosslinking reactions by means of compounds containing epoxy groups at a temperature below the melting temperature of the polymer to be crosslinked.

Amines are particularly preferably used as accelerators. In a further embodiment III of the polymer foam layer, the polymer foam layer, in particular the matrix material of the polymer foam layer, contains at least one vinyl aromatic block copolymer. The polymer foam layer, in particular the matrix material of the polymer foam layer, preferably contains at least one vinyl aromatic block copolymer which contains at least one polymer block A which is predominantly formed by the polymerization of vinyl aromatic compounds and at least one polymer block B which is predominantly formed by the polymerization of conjugated dienes, the The proportion of 1,2-linked conjugated diene in the B block is less than 30% by weight, preferably less than 20% by weight (can be determined by means of ¹ H-NMR).

The vinyl aromatic block copolymer described above is preferably contained in the polymer foam as an elastomer component in embodiment III considered here. If the polymer foam contains several elastomer components, it is preferably contained in the polymer foam to an extent of at least 50% by weight, based on the total weight of all elastomer components.

The polymer block A of the preferred vinyl aromatic block copolymer is formed predominantly by the polymerization of vinyl aromatic compounds. This means that the block A typically emerged from a polymerization in which more than 50% by weight of the monomers used are vinyl aromatics. More preferably, the polymer block A emerged from a polymerization in which exclusively vinyl aromatics were used as monomers.

The polymer block B of the preferred vinyl aromatic block copolymer is formed predominantly by the polymerization of conjugated dienes. This means that block B emerged from a polymerization in which more than 50% by weight of the monomers used are conjugated dienes. More preferably, the polymer block B emerged from a polymerization in which exclusively conjugated dienes were used as monomers.

The proportion of 1,2-linked conjugated diene in the B block of the preferred vinyl aromatic block copolymer is less than 30% by weight, preferably less than 20% by weight. This proportion is more preferably less than 15% by weight, in particular 8 to 12% by weight. The proportion of 1,2-linked conjugated diene in the B block is the proportion by weight of conjugated diene which has been polymerized by 1,2 addition (as opposed to 1,4 addition), based on the Production of the polymer block B total monomer mass used. The 1,2 addition of conjugated diene results in a vinylic side group in the polymer block B, while the 1,4-addition of conjugated diene leads to a vinylic functionality in the main chain of the polymer block B. The 1,2 addition of a conjugated diene thus means that the incorporation of the monomer into the polymer chain takes place either via positions C1 and C2 or via positions C3 and C4 (for example in the case of isoprene as conjugated diene). In the 1,4-addition of a conjugated diene, on the other hand, it runs through positions C1 and C4.

The vinyl aromatic block copolymer preferably has a structure AB, ABA, (AB) _n , (AB) _n X or (ABA) nX, in which the blocks A independently of one another for a polymer formed by polymerization of at least one vinyl aromatic, the blocks B independently of one another for a polymer formed by the polymerization of conjugated dienes with 4 to 18 carbon atoms,

X stands for the remainder of a coupling reagent or initiator and n stands for an integer> 2.

Particularly preferred in embodiment III are all vinyl aromatic block copolymers of the polymer foam layer according to the invention block copolymers with a structure AB, ABA, (AB) n, (AB) nX or (ABA) _n X as set out above. The polymer foam layer can thus also contain mixtures of different vinyl aromatic block copolymers with a structure as described above.

The blocks B are also referred to as rubber-like blocks or soft blocks and the blocks A as glass-like blocks or hard blocks. Particularly preferably, at least one vinyl aromatic block copolymer of the polymer foam layer has a structure AB, ABA, (AB) 2X, (AB) 3X or (AB) ₄ X, where A, B and X are as defined above. All vinylaromatic block copolymers very particularly preferably have a structure AB, ABA, (AB) 2X, (AB) 3X or (AB) ₄ X, where A, B and X are as defined above. In particular, in embodiment III, the polymer foam layer contains a mixture of block copolymers with a structure AB, ABA, (AB) 2X, (AB) sX or (AB) ₄ X, which is more preferably at least diblock copolymers AB and / or triblock copolymers ABA and / or ( AB) 2X contains, in particular, a mixture of diblock copolymers (AB) and triblock copolymers (ABA), for example of two types of vinyl aromatic block copolymers with a different weight ratio of diblock copolymers (AB) and triblock copolymers (ABA). The vinyl aromatic block copolymers preferably have a diblock copolymer content of 0% by weight to 70% by weight, more preferably from 15% by weight to 65% by weight, in particular from 30 to 60% by weight, very particularly preferably from 40 to 60% by weight, for example from 51.5% by weight to 55% by weight.

The block copolymers resulting from the A and B blocks can contain the same or different B blocks.

In preferred vinyl aromatic block copolymers, in particular in preferred styrene block copolymers, the proportion of polyvinyl aromatics, in particular of polystyrene, is preferably at least 12% by weight, more preferably at least 18% by weight, particularly preferably at least 25% by weight and also preferably at most 45% by weight % and more preferably at most 35% by weight.

Instead of the preferred polystyrene blocks, polymer blocks based on other aromatic-containing homopolymers and copolymers with glass transition temperatures of greater than 75 ° C. can also be used as vinyl aromatics. Preference is given to homo- and / or copolymer blocks based on C8 to C12 aromatics, such as, for example, α-methylstyrene. It can contain the same or different A-blocks.

The polymer block A is preferably formed predominantly by the polymerization of styrene and / or α-methylstyrene. The block A can thus be present as a homo- or copolymer. Block A is particularly preferably a polystyrene. The vinyl aromatic block copolymers very particularly preferably have polystyrene end blocks.

The polymer block B is preferably formed predominantly by polymerization of conjugated dienes selected from the group consisting of butadiene, isoprene, ethylbutadiene, phenylbutadiene, pentadiene, hexadiene, ethylhexadiene, dimethylbutadiene, α-farneses and β-farneses and any mixtures of these monomers; like block A, it can be present as a homopolymer or as a copolymer. Block B is particularly preferably formed predominantly by polymerizing butadiene and / or isoprene. Block B is very particularly preferably a polybutadiene; this shows an even better aging behavior compared to polyisoprene.

A blocks are also referred to as “hard blocks” in the context of this invention. B blocks are also called “soft blocks” or “elastomer blocks”. This reflects the selection of the blocks according to their glass transition temperatures, which for the A blocks is preferably at least 25 ° C., in particular at least 50 ° C., and for B blocks is preferably at most 25 ° C, particularly preferably at most -25 ° C, and in particular at most -50 ° C.

In embodiment III, the proportion of all the vinyl aromatic block copolymers, in particular the styrene block copolymers, in the polymer foam layer is preferably at least 35% by weight, based on the total weight of the polymer foam layer. Such a proportion advantageously improves the cohesion of the polymer foam layer.

The maximum proportion of all of the vinyl aromatic block copolymers, in particular the styrene block copolymers, in the polymer foam layer is preferably a maximum of 75% by weight, in particular a maximum of 65% by weight, very particularly preferably a maximum of 55% by weight.

The polymer foam of embodiment III preferably contains at least one adhesive resin. In principle, one or more tackifier resins can be included. In this way, the foam is advantageously given pressure-sensitive adhesive properties.

According to the general understanding of the art, an “adhesive resin” is understood to mean a low molecular weight, oligomeric or polymeric resin which increases the adhesion (the tack, the inherent tack) of the PSA in comparison to the PSA which does not contain adhesive resin but is otherwise identical.

The adhesive resin preferably has a DACP (diacetone alcohol cloud point) of> 0 ° C, more preferably> 10 ° C, in particular> 30 ° C, and a softening temperature (ring & ball) of> 70 ° C, preferably> 100 ° C.

The respective adhesive resin particularly preferably has a DACP value of a maximum of 45 ° C. if there are no isoprene blocks in the elastomer phase, or of a maximum of 60 ° C. if there are isoprene blocks in the elastomer phase. The softening temperature of the respective adhesive resin is particularly preferably a maximum of 150.degree.

Preferably the adhesive resin is a hydrocarbon resin; In particular, it is selected from the group consisting of hydrogenated and non-hydrogenated polymers of dicyclopentadiene, non-hydrogenated, partially, selectively or fully hydrogenated hydrocarbon resins based on C5, C5 / C9 or C9 monomer streams and polyterpene resins based on a-pinene and / or ß-pinene and / or d-limonene. These tackifier resins can be used either alone or as a mixture. In principle, both solid and liquid resins can be used at room temperature. Adhesive resins, hydrogenated or non-hydrogenated, which also contain oxygen, can optionally contain up to a maximum proportion of 25% by weight, based on the total mass of the adhesive resins contained in the polymer foam, in the polymer foam of embodiment III such as rosin and / or rosin ester resins and / or terpene phenolic resins.

The adhesive resin is particularly preferably a non-hydrogenated hydrocarbon resin, in particular based on α-pinene. In addition to high cohesion, these resins advantageously also give the polymer foam a very high level of adhesion, in particular even at high temperatures.

The polymer foam of embodiment III preferably contains 20 to 60% by weight, particularly preferably 30 to 50% by weight, based in each case on the total weight of the polymer foam, of at least one adhesive resin.

Foaming

Basically, foams can be produced in two ways: on the one hand by the action of a propellant gas, either added as such or resulting from a chemical reaction, on the other hand by incorporating hollow spheres into the material matrix. Foams made in the latter way are known as syntactic foams.

Physical blowing agents are any naturally occurring atmospheric material that is gaseous at the temperature and pressure at which the foam emerges from the nozzle. Physical propellants can be introduced, ie injected, into the matrix material as a gas, as a supercritical fluid or as a liquid. The choice of physical blowing agent used depends on the desired properties of the resulting foams. Other factors to consider when choosing a blowing agent are its toxicity, vapor pressure profile, ease of handling, and solubility with respect to the polymeric materials used. Flammable propellants such as pentane, butane, and other organic materials such as fluorocarbons and chlorofluorocarbons can be used; however, preference is given to non-flammable, non-toxic, non-ozone-depleting propellants because they are easier to use, there are fewer concerns about their effects on the environment, etc. Preferred physical propellants are carbon dioxide, nitrogen, SF6, nitrogen oxides, perfluorinated liquids such as C2F6, noble gases such as Helium, argon and xenon, air (typically a mixture of nitrogen and oxygen), and mixtures of these materials. Alternatively, chemical blowing agents can also be used for foaming. Suitable chemical propellants include mixtures of sodium bicarbonate and citric acid, dinitrosopentamethylenetetramine, p-toluenesulfonyl hydrazide, 4-4'-oxybis (benzenesulfonylhydrazide, azodicarbonamide (1,1'-azobisformamide), p-toluenesulfonoga-tetyl-tetrazyl-prazole, 5-phenrazyl-analogs , Diisopropyl hydrazodicarboxylate, 5-phenyl-3,6-dihydro-1, 3,4-oxadiazin-2-one and sodium borohydride.

The polymer foam layer preferably contains microballoons; in this case it is at least foamed using microballoons. If it is only foamed using microballoons, it is a syntactic foam.

“Microballoons” are understood to mean elastic and thus expandable microspheres in their basic state, which have a thermoplastic polymer shell. These balls are filled with low-boiling liquids or liquefied gas. In particular, polyacrylonitrile, PVDC, PVC or polyacrylates are used as the shell material. Hydrocarbons of the lower alkanes, for example isobutane or isopentane, which are enclosed as a liquefied gas under pressure in the polymer shell, are particularly common as the low-boiling liquid.

By acting on the microballoons, in particular by applying heat, the outer polymer shell softens. At the same time, the liquid propellant in the envelope changes into its gaseous state. The microballoons expand irreversibly and expand three-dimensionally. The expansion is finished when the internal and external pressures equalize. Since the polymer shell is retained, a closed-cell foam is achieved.

A large number of types of microballoons are commercially available, which differ essentially in terms of their size (6 to 45 μm diameter in the unexpanded state) and their starting temperatures (75 to 220 ° C.) required for expansion. Unexpanded types of microballoons are also available as aqueous dispersions with a solids or microballoon content of approx. 40 to 45% by weight, and also as polymer-bound microballoons (masterbatches), for example in ethylene vinyl acetate with a microballoon concentration of approx. 65% by weight. Both the microballoon dispersions and the masterbatches, like the unexpanded microballoons, are suitable as such for producing the polymer foam layer.

The polymer foam can also be produced with so-called pre-expanded microballoons. In this group, expansion takes place before it is mixed into the polymer matrix. The polymer foams can also be produced with foamed particles, that is to say with expanded or expandable beads made of, in particular, polystyrene, polypropylene, thermoplastic polyurethane or cellulose acetate, for which the term “beads” has become established. Particles of already foamed plastics are mixed into the polymer matrix, which cause the density to decrease. The particles can also be placed in the polymer matrix without being foamed and only then foamed. Furthermore, the polymer foam can also consist of “beads” thermally connected to one another, in particular welded, possibly pre-expanded, so that in this case no further surrounding matrix is present.

The polymer foam can contain anti-aging agents, e.g. primary antioxidants such as sterically hindered phenols, secondary antioxidants such as phosphites or thioethers and / or carbon radical scavengers. It is also possible, for example, to use light stabilizers such as UV absorbers or sterically hindered amines; Antiozonants; Metal deactivators and / or processing aids may be included.

The polymer foam can also contain fillers such as silicon dioxide, glass (ground or in the form of spheres), aluminum oxides, zinc oxides, calcium carbonates, titanium dioxide, carbon blacks, etc., as well as pigments, dyes and / or optical brighteners.

Outer pressure sensitive adhesive layer

According to the invention, a pressure-sensitive adhesive or a pressure-sensitive adhesive is understood, as is customary in common parlance, to be a substance which is permanently tacky and also tacky at least at room temperature. It is characteristic of a pressure-sensitive adhesive that it can be applied to a substrate by pressure and remains adhered there, the pressure to be applied and the duration of this pressure not being defined in more detail. In general, but basically depending on the exact type of pressure-sensitive adhesive as well as the substrate, the temperature and the air humidity, the application of a short-term, minimal pressure, which does not go beyond a light touch for a short moment, is sufficient to achieve the adhesive effect in other cases a longer period of exposure to a higher pressure may be necessary.

Pressure-sensitive adhesives have special, characteristic viscoelastic properties which lead to permanent tack and adhesiveness. They are characterized by the fact that when they are mechanically deformed, both viscous flow processes and the build-up of elastic restoring forces occur. Both processes are related to each other in terms of their respective share, depending on the exact one Composition, the structure and the degree of crosslinking of the PSA as well as the speed and duration of the deformation and the temperature.

The proportionate viscous flow is necessary to achieve adhesion. Only the viscous components, often caused by macromolecules with relatively high mobility, enable good wetting and flow onto the substrate to be bonded. A high proportion of viscous flow leads to high pressure-sensitive tack (also referred to as tack or surface tack) and thus often also to high adhesion. Strongly cross-linked systems, crystalline or glass-like solidified polymers are generally not or at least only slightly tacky due to the lack of flowable components.

The proportional elastic restoring forces are necessary to achieve cohesion. They are caused, for example, by very long-chain and strongly tangled macromolecules as well as by physically or chemically cross-linked macromolecules and enable the forces acting on an adhesive bond to be transmitted. They lead to the fact that an adhesive connection can withstand a permanent load acting on it, for example in the form of permanent shear stress, to a sufficient extent over a longer period of time.

The storage modulus (G ‘) and loss modulus (G”) that can be determined by means of dynamic mechanical analysis (DMA) are used for a more precise description and quantification of the amount of elastic and viscous components as well as the relationship between the components. G ‘is a measure for the elastic part, G“ is a measure for the viscous part of a substance. Both sizes are dependent on the deformation frequency and the temperature.

The sizes can be determined with the aid of a rheometer. The material to be examined is exposed to a sinusoidal oscillating shear stress, for example in a plate-plate arrangement. In devices controlled by shear stress, the deformation is measured as a function of time and the time offset of this deformation with respect to the introduction of the shear stress. This time offset is referred to as the phase angle d.

The storage modulus G 'is defined as follows: G' = (t / g) _* cos (δ) (T = shear stress, y = deformation, d = phase angle = phase shift between shear stress and deformation vector). The definition of the loss modulus G "is: G" = (t / g) · sin (δ) (T = shear stress, g = deformation, d = phase angle = phase shift between shear stress and deformation vector).

In particular, a mass is considered a pressure-sensitive adhesive and is defined as such within the meaning of the invention if at 23 ° C in the deformation frequency range of 10 ° to 10 ¹ rad / sec both G 'and G ″ are at least partially in the range of 10 ³ up to 10 ⁷ Pa lie. “Partly” means that at least a section of the G 'curve lies within the window that is defined by the deformation frequency range from 10 ° up to and including 10 ¹ rad / sec (abscissa) and the range of G' values from 10 ^{3 inclusive} up to and including 10 ⁷ Pa (ordinate), and if at least a section of the G “curve is also within the corresponding window.

The outer pressure-sensitive adhesive layer preferably contains at least 50% by weight, more preferably at least 70% by weight, particularly preferably at least 90% by weight, in particular at least 95% by weight, for example at least 97% by weight , in each case based on the total weight of the pressure-sensitive adhesive layer, one or more

Poly (meth) acrylate (s).

The outer pressure-sensitive adhesive layer particularly preferably contains at least 50% by weight, more preferably at least 70% by weight, particularly preferably at least 90% by weight, in particular at least 95% by weight, for example at least 97% by weight %, in each case based on the total weight of the pressure-sensitive adhesive layer, one or more

Poly (meth) acrylate (s), which can be traced back to the following monomer composition:

Moni) at least one acrylic acid ester and / or methacrylic acid ester of the formula (2)

CH ₂ = C (R ^IM ) (COOR ^iv ) (2), in which R ^m = H or CH ₃ and R ^{IV is} an alkyl radical having 4 to 12 carbon atoms;

Mon2) at least one olefinically unsaturated monomer with at least one functional group selected from the group consisting of carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, hydroxyl groups,

Acid anhydride groups, epoxy groups and amino groups

Mon3) optionally at least one acrylic acid ester and / or methacrylic acid ester of the formula (3)

CH ₂ = C (R ^V ) (COOR ^vi ) (3), in which R ^v = H or CH3 and R ^{VI is} an alkyl radical having 1 to 3 carbon atoms.

The monomer composition can contain one or more monomers Moni, Mon2 and Mon3, independently of one another.

Monomeric moni are preferably at least 70% by weight, more preferably at least 80% by weight, based in each case on the total weight of the

Monomer composition contained in this. Monomeric Mon2 are preferably contained in the monomer composition in an amount of 1 to 15% by weight, based on the total weight of the latter.

Monomeric Mon3, if present at all, is preferably present in an amount of 5 to 15% by weight, based on the total weight of the monomer composition.

The monomers moni preferably comprise at least one branched monomer. Particularly preferred are the monomers a) selected from the group consisting of n-butyl acrylate, n-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, n-amyl acrylate, n-hexyl acrylate, n-hexyl methacrylate, n-heptyl acrylate, n-octyl acrylate, n -Octyl methacrylate, n-nonylacrylate, isobutyl acrylate, isooctyl acrylate, isooctyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate, 2-propylheptyl acrylate and isobornyl acrylate. The monomers Moni are particularly preferably selected from n-butyl acrylate, 2-ethylhexyl acrylate and isobornyl acrylate.

The monomers Mon2 are preferably selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, aconitic acid, dimethylacrylic acid, β-acryloyloxypropionic acid, trichloroacrylic acid, vinyl acetic acid, vinylphosphonic acid, maleic anhydride, hydroxyhexyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxyhexyl acrylate, hydroxypropyl acrylate, hydroxyhexyl acrylate, hydroxypropyl acrylate, hydroxyhexyl acrylate, hydroxypropyl methacrylate, fumaric acid, crotonic acid, fumaric acid, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxyhexyl acrylate, hydroxypropyl methacrylate, hydroxyhexyl acrylate, hydroxypropyl methacrylate, maleic acid, fumaric acid, crotonic acid, fumaric acid, crotonic acid , Allyl alcohol, glycidyl acrylate and glycidyl methacrylate. Acrylic acid is particularly preferred as monomer Mon2.

The monomer Mon3, if present at all, is preferably methyl acrylate.

The poly (meth) acrylate of the outer pressure-sensitive adhesive layer on a monomer composition is particularly preferred

70 to 95% by weight of 2-ethylhexyl acrylate, n-butyl acrylate and / or isobornyl acrylate; in particular n-butyl acrylate and 2-ethylhexyl acrylate;

1 to 15% by weight acrylic acid; and

0 to 15 wt .-% methyl acrylate returned.

In particular, the poly (meth) acrylate of the outer pressure-sensitive adhesive layer is composed of a monomer composition

1 to 15% by weight acrylic acid; and 0 to 15 wt .-% methyl acrylate returned.

The poly (meth) acrylates of the outer pressure-sensitive adhesive layer are preferably crosslinked thermally, in particular covalently and / or coordinatively. Preferred covalent crosslinking agents are epoxy compounds, preferred coordinative crosslinking agents are aluminum chelates.

The weight-average molecular weight M _{w of} the poly (meth) acrylates of the outer pressure-sensitive adhesive layer is preferably from 20,000 to 2,000,000 g / mol, particularly preferably from 100,000 to 1,500,000 g / mol, in particular from 200,000 to 1,200,000 g / mol. The information on the average molecular weight M _w in this document relates to the determination by gel permeation chromatography (see experimental section).

Outer thermoplastic film

“Outer thermoplastic film” means that the thermoplastic film faces outwards and thus completes the structure of the adhesive tape on its side.

A thermoplastic film has little or no adhesive properties, so that in every conceivable structure of the adhesive tape according to the invention, which comprises an outer thermoplastic film, it closes the side with the weaker bond strength. If the adhesive tape thus comprises an outer thermoplastic film, it has a lower bond strength on its side equipped with the outer thermoplastic film than on the opposite side, or it has no bond strength on its side equipped with the outer thermoplastic film.

The thermoplastic film preferably comprises at least one polymer selected from the group consisting of thermoplastic polyolefins (TPE-E or TPO), in particular thermoplastic polyolefin elastomers (POE) and thermoplastic polyolefin plastomers (POP); thermoplastic polystyrene elastomers (TPE-S or TPS), in particular styrene block copolymers (SBC); thermoplastic polyurethane elastomers (TPE-U or TPU); thermoplastic polyester elastomers and copolyesters (TPE-E or TPC); thermoplastic copolyamides (TPE-A or TPA); and thermoplastic vulcanizates as well as cross-linked thermoplastic polyolefin elastomers (TPE-V or TPV).

In particular, the thermoplastic film consists of at least one, particularly preferably one, polymer selected from the group consisting of thermoplastic polyolefins (TPE-E or TPO), in particular thermoplastic polyolefin elastomers (POE) and thermoplastic polyolefin elastomers (POP); thermoplastic polystyrene elastomers (TPE-S or TPS), in particular styrene block copolymers (SBC); thermoplastic polyurethane elastomers (TPE-U or TPU); thermoplastic polyester elastomers and copolyesters (TPE-E or TPC); thermoplastic copolyamides (TPE-A or TPA); and thermoplastic vulcanizates as well as cross-linked thermoplastic polyolefin elastomers (TPE-V or TPV).

Tape construction

The structure or the layer sequence of an adhesive tape according to the invention comprises several variants. In one embodiment, the structure of the adhesive tape of the invention is limited to the polymer foam layer and an outer pressure-sensitive adhesive layer. In this case, the adhesive tape of the invention thus consists of a) a polymer foam layer and b) an outer pressure-sensitive adhesive layer.

The required weaker bond strength on the side opposite the outer PSA layer results in this case from the fact that the exposed side of the polymer foam layer has a weaker bond strength than the PSA layer. In this embodiment, the polymer foam layer preferably corresponds to a polymer foam layer of embodiment II described there; the polymer foam layer, in particular the matrix material of the polymer foam layer, therefore preferably contains at least one poly (meth) acrylate. All the more detailed configurations described in the context of embodiment II of the polymer foam layer apply here accordingly.

In principle, the invention also comprises an embodiment in which an outer pressure-sensitive adhesive layer is arranged on each side of the polymer foam layer. Of course, following the basic idea of the invention, the two outer pressure-sensitive adhesive layers are not identical in this case and differ in particular with regard to their bond strength.

In a further embodiment of the invention, the adhesive tape of the invention consists of a) a polymer foam layer and b) an outer thermoplastic film.

In this embodiment, the polymer foam layer preferably corresponds to a polymer foam layer of embodiment III described there; the The polymer foam layer, in particular the matrix material of the polymer foam layer, therefore preferably contains at least one vinyl aromatic block copolymer. All the more detailed configurations described in the context of embodiment III of the polymer foam layer apply here accordingly.

In this embodiment, the polymer foam layer is in particular sufficiently (adhesive) tacky to enable a sufficiently strong layer bond between itself and the outer thermoplastic film.

In a further embodiment of the invention, the adhesive tape consists of a) a polymer foam layer; b1) an outer pressure-sensitive adhesive layer on one side of the polymer foam layer and b2) an outer thermoplastic film on the side of the polymer foam layer opposite the outer pressure-sensitive adhesive layer.

In this embodiment, the polymer foam layer preferably corresponds to a polymer foam layer of embodiment II described there; the polymer foam layer, in particular the matrix material of the polymer foam layer, therefore preferably contains at least one poly (meth) acrylate. All the more detailed configurations described in the context of embodiment II of the polymer foam layer apply here accordingly.

In a further embodiment, the adhesive tape comprises, in addition to the polymer foam layer b1), an outer pressure-sensitive adhesive layer on one side of the polymer foam layer; b2) an outer thermoplastic film on the side of the polymer foam layer opposite the outer pressure-sensitive adhesive layer; and c) a further pressure-sensitive adhesive layer on the side of the polymer foam layer opposite the outer pressure-sensitive adhesive layer.

In this embodiment, the further pressure-sensitive adhesive layer is thus located between the polymer foam layer and the outer thermoplastic film; it preferably connects the polymer foam layer with the outer thermoplastic film.

The statements made in relation to the outer pressure-sensitive adhesive layer apply to the further pressure-sensitive adhesive layer. The further pressure-sensitive adhesive layer and the the outer pressure-sensitive adhesive layer is identical in terms of its composition; in particular, they are identical both in terms of their composition and in terms of their layer thickness.

In this embodiment too, the polymer foam layer preferably corresponds to a polymer foam layer of embodiment II described there; the polymer foam layer, in particular the matrix material of the polymer foam layer, therefore preferably contains at least one poly (meth) acrylate. All the more detailed configurations described in the context of embodiment II of the polymer foam layer apply here accordingly.

use

Another object of the invention is the use of an adhesive tape according to the invention for sealing a connection between two components. The adhesive tape according to the invention advantageously allows rapid gluing and thus rapid production of the seal without slipping and without the need for curing. Waterproof and less susceptible to corrosion seals can be provided. In addition, a simplified dismantling of the connection is possible, in that the component connected to the weaker adhesive side can be easily removed.

Preferably, the connection between the two components is initially effected in a different manner than by gluing; the connection between the components is particularly preferably a mechanical connection, for example a screw connection.

The two components are basically arbitrary, the term “components” is understood in a very broad sense. The two components are preferably the housing and the cover of a vehicle battery; particularly preferably, when such a connection is sealed, the weaker adhesive side of the adhesive tape faces the cover. Furthermore, the components can also belong to an electronic device, e.g. a smartphone or the like.

The adhesive tape according to the invention is likewise preferably pulled off a cross-wound reel within the scope of the use according to the invention; in particular, this step is automated. Examples

Test methods

Gel permeation chromatography to determine the molecular weight:

The details of the molecular weight in this document relate to the determination by gel permeation chromatography. The determination is carried out on 100 ml clear-filtered sample (sample concentration 4 g / l). Tetrahydrofuran with 0.1% by volume of trifluoroacetic acid is used as the eluent. The measurement takes place at 25 ° C. A column type PSS-SDV, 5 m, 10 ³ Å, ID 8.0 mm 50 mm is used as the guard column. The columns of the type PSS-SDV, 5 m, 10 ³ Å as well as 10 ⁵ Å and 10 ⁶ Å, each with ID 8.0 mm x 300 mm, are used (columns from Polymer Standards Service; detection using a Shodex RI71 differential refractometer) . The flow rate is 1.0 ml per minute. The calibration is carried out against PMMA standards (polymethyl methacrylate calibration).

Water permeability:

5 mm narrow strips were cut out of the adhesive tape to be examined and stuck onto a square metal plate (external dimensions 80 mm × 80 mm × 5 mm). The strips were arranged in such a way that they form a closed square contour. The ends of one strip were each connected flush with the side surface of the next end of the strip.

A paste (KMn0) was then applied to the inside of the square, which turns a distinct purple color on contact with water. An identical metal plate was then placed on the structure and screwed. The screws were outside the square of strips of tape. The distance between the metal plates was set to exactly 2 mm by means of 2 pieces of 1 mm thick shim washers. This setup ensured that the water-reactive paste is in a closed space within the adhesive tape strips. A penetration of water would be recognizable by a discoloration and indicate a leak in the adhesive tape.

The entire sample was then placed in a water bath, which was then placed in an autoclave. First, a slight overpressure of 0.3 bar was applied; In a second test, an overpressure of 3 bar then simulated a water column of 30 m. After 30 minutes' storage under water in the autoclave, the overpressure was released The composite was removed and examined for discoloration of the KMnC> 4. A discoloration indicates water permeability of the adhesive tape, no discoloration indicates impermeability to water (result “water permeable yes / no”).

Re-detachability of the bonded substrate (simulation of the re-detachment of a bonded battery cover; reopenability):

The adhesive tape was applied with the more strongly adhesive side to an aluminum plate (450 × 250 mm, 2.5 mm thick) at a distance of 30 mm from the edge of the plate once all the way around. Another aluminum plate (450 x 250 mm, 1 mm thick) with identical dimensions was attached to the free side (from above). 2 mm thick shims were inserted into the joints on each side, then the composite was pressed together in a screw clamp. The aluminum plates were then screwed together using holes in the corners of the plates for this purpose.

The composite formed in this way was stored for 10 days in a climatic chamber at 40 ° C. and 100% relative humidity. After removal, it was reconditioned for 24 hours at 23 ° C. and 50% relative humidity.

The screws and shims were then removed and a tensioning belt was inserted into the joint on one of the shorter sides and connected to a testing machine (Zwick). The upper (1 mm thick) plate was pulled off at a speed of 300 mm / min at an angle of 90 °, and the maximum force required for this was measured. Table 1 shows the mean value from three measurements.

Adhesive tapes used

A - tesa ^® 61102 (closed-cell EPDM rubber foam, coated on one side with an acrylate adhesive, total thickness 3,200 μm; tesa)

B - tesa ^® ACX ^plus 70730 High Resistance (double-sided acrylate

Foam tape, coated on both sides with acrylate pressure-sensitive adhesive, total thickness 2,900 gm; tesa), laminated on one side with a thermoplastic polyurethane film (Platilon ^® U04 / PE, 30 gm; Bayer)

C - tesa ^® ACX ^plus 70730 High Resistance, where the acrylate pressure-sensitive adhesive was only applied on one side, i.e. the acrylate foam was exposed on one side (see B, total thickness 2,850 μm; tesa)

D - tesa ^® 92111 HiP - High initial performance, 3x glued to itself,

Total thickness 3,300 pm; tesa); Laminated on one side with a thermoplastic polyurethane film (Platilon ^® U04 / PE, 30 pm; Bayer)

E - tesa ^® ACX ^plus 70730 High Resistance (double-sided acrylate foam tape, coated on both sides with acrylate pressure-sensitive adhesive, total thickness 2,900 μm; tesa); Comparative example

Table 1: Test Results

Compare = comparative example

Claims

1. Adhesive tape with different adhesive strength on both main sides, comprising a) a polymer foam layer and b) an outer pressure-sensitive adhesive layer and / or an outer thermoplastic film on each side of the polymer foam layer; characterized in that if the adhesive tape comprises an outer pressure-sensitive adhesive layer, it has a higher bond strength on its side equipped with the outer pressure-sensitive adhesive layer than on the opposite side and / or, if the adhesive tape comprises an outer thermoplastic film, it has a higher bond strength on its side with the outer thermoplastic film Film-equipped side has a lower adhesive strength than on the opposite side.

2. Adhesive tape according to claim 1, characterized in that the polymer foam layer comprises at least 35% by weight, based on the total weight of the polymer foam layer, of one or more polymers selected from the group consisting of polyolefins; Polyurethanes; Polyvinyl chloride (PVC); Blends of PVC and nitrile rubber; Terpolymers of ethylene, propylene and a non-conjugated diene (EPDM); Copolymers of ethylene and an ethylene substituted with a polar group; Blends of polyethylene and a polymer of an ethylene substituted with a polar group; Poly (meth) acrylates; Contains blends of poly (meth) acrylate and synthetic rubber and mixtures of two or more of the aforementioned polymers.

3. Adhesive tape according to one of the preceding claims, characterized in that the polymer foam layer contains at least one poly (meth) acrylate.

4. Adhesive tape according to one of the preceding claims, characterized in that the polymer foam layer contains microballoons.

5. Adhesive tape according to one of the preceding claims, characterized in that the adhesive tape consists of a) a polymer foam layer and b) an outer pressure-sensitive adhesive layer on one side of the polymer foam layer.

6. Adhesive tape according to one of claims 1 to 4, characterized in that the adhesive tape consists of a) a polymer foam layer and b) an outer thermoplastic film on one side of the polymer foam layer.

7. Adhesive tape according to one of claims 1 to 4, characterized in that the adhesive tape consists of a) a polymer foam layer, b) an outer pressure-sensitive adhesive layer on one side of the polymer foam layer and c) an outer thermoplastic film on the other side of the polymer foam layer.

8. Use of an adhesive tape according to one of claims 1 to 7 for sealing a connection between two components.

9. Use according to claim 8, characterized in that the connection between the components is a mechanically effected connection.